Messages In 'Wait' State in RWB Monitor

Recently IDOCS have been showing up in the RWB in a 'wait' state. Using SXMB_MONI, the messages are listed as 'Scheduled'. The only way to release these IDOCs is to go into Monitor for Message Packages under the Monitoring Tab and release via this transaction. Nothing was changed in the Mapping Interfaces. I can not determine why these messages are hung in this 'wait' state.